Nicholas Thompson carded a seven under-par 65 to join Daniel Summerhays at the top of the leaderboard as the Sanderson Farms Championship finally got back on track on day three.
Extensive weather delays on the first two days had left 59 players with their second round incomplete on Saturday morning, with 18-hole leader Summerhays among them.
He produced a five-under-par 67 to lead by four at 14 under as the tournament belatedly reached its halfway point, but he could only manage a 69 on his third circuit, allowing Thompson in.
Thompson's round got off to an unpromising start with a bogey at the first, but from there he was flawless, carding eight birdies to claim the clubhouse lead at 17 under.
He was eventually joined at that mark by Summerhays, who returned to birdie the last after another short weather delay when his was the only group still on course.
The pair led by two from a group of four more Americans: Chad Campbell and Cameron Beckman, who both matched Thompson's third-round 65, as well as Woody Austin and Kyle Reifers.
"I don't know what score it's going to take, but it's going to be a good one, regardless," Thompson told www.pgatour.com. "Guys have gone low and the golf course is in perfect condition."
Thompson, whose sister Lexi is joint third heading into the final round of the LPGA Marathon Classic in Ohio, added: "Hopefully it'll be a great day for the Thompson family."
With further bad weather forecast, play will get under way at 8am local time on the final day, with groups of three going from the first and 10th tees in an attempt to wrap up the tournament before the storms hit.
Also in with a shout will be Brendon Todd, Bill Lunde and Vaughn Taylor on 14 under, as well as Rory Sabbatini and Jim Herman on 13 under.